Accompanied with continuous technology breakthroughs, touch panels are prevailingly applied in various electronic devices from smart phones, digital cameras to tablet PCs. Popularization of touch panels not only eliminates the provision of keypads but also enlarges display screens of common electronic devices.
FIG. 1 shows a perspective view of a monitor 30, which comprises a transparent touch panel 22 disposed on a display panel 20. When the touch panel 22 detects a touch event that a surface 24 of the touch panel 22 is touched or approached by an object, the touch panel 22 sends out a corresponding signal to a processor (not shown) for subsequent corresponding operations. For example, as shown in FIG. 1, when a finger presses the monitor 30 at two touched points T1 and T2, the monitor generates corresponding tracking signals S1 and S2 carrying information such as coordinates and pressure corresponding to the touched points.
A touch panel adopting a projected capacitive touch (PCT) technology comprises numerous capacitance sensing nodes thereupon. Each of the capacitance sensing nodes comprises at least one electrode. A sensing principle of the PCT technology, for example, may be based on a variation of mutual capacitance or self capacitance, which is commonly referred to as a mutual touch sensing technique or a self touch sensing technique, respectively. For mutual touch sensing technique, a change in capacitance between two electrodes induced by a touch event is measured. In self touch sensing technique, a change in capacitive load of a single electrode induced by a touch event is measured. Furthermore, the measuring of each capacitance sensing point is independent from the measuring of other capacitance sensing points. Therefore, a relationship between capacitances and coordinates substantially reflects information such as a quantity, a center position and an area size of a touched point on the surface of the touch panel.